What soil mix for my japanese maples

[Bonsainoob88]

Hello everyone , I am wondering what people reccomend as a good substrate for my Japanese maples. I have Akadama, eracacious compost, peat moss , pumice and fine pine bark . So I was hoping to make something up out of that . After researching I am going to try a 50%akadama , 30% lava rock and 20% peat moss mix for deciduous. I aim to repot in autumn once the leaves has dropped as I believe this us the right time.
So please tell me if I am making any obvious mistakes and stop me from killing my trees
any advice is great thanks!

 

[Bonsai Nut]

I would skip the peat moss because it will clog up your soil. Otherwise, akadama, lava, and fine pine bark should work well. The pine bark will add acidity to your soil without clogging it.

The best time to repot Japanese maples is the spring as they are just starting to come out of dormancy. You do NOT want to repot in Autumn as the trees are going INTO dormancy, since you don't want to mess with the roots or cause damage to the tree that it will not be able to recover from prior to winter dormancy. You want your deciduous trees to be at their strongest going into winter.

 

[fredman]

^^^^^^^^^^^^^^
what he said

 

[rodeolthr]

FWIW, and not to start an argument, but I do all of my repotting in November. This is the time that I move my maples from nursery pots into plastic training pots. They routinely freeze solid for about 2 weeks, and by some stroke of luck always come out in the spring looking happy. All of my trees (hundreds) are sitting outside on the ground or atop concrete block walls and exposed to everything that a PNW winter offers. I'm not suggesting this for others, it's just what I do since I'm not here in the spring to do repotting. I am one zone cooler than you also.

 

[caerolle]

FWIW, and not to start an argument, but I do all of my repotting in November. This is the time that I move my maples from nursery pots into plastic training pots. They routinely freeze solid for about 2 weeks, and by some stroke of luck always come out in the spring looking happy. All of my trees (hundreds) are sitting outside on the ground or atop concrete block walls and exposed to everything that a PNW winter offers. I'm not suggesting this for others, it's just what I do since I'm not here in the spring to do repotting. I am one zone cooler than you also.

Zone 8a doesn't seem that harsh? I live on the border between 6a and 5b and that does worry me (first wintering of A. palmatum!)

 

[rodeolthr]

@caerolle , you are correct, it's quite mild by other standards and considering that I moved here from zone 4. The OP is in zone 9 though, so I thought that my experience might be relevant.

 

[Bonsainoob88]

The thing I don't really understand is how the UK zone9 climate is wildly different to a USA zone 9 but they're both zone 9

 

[Bonsainoob88]

I would skip the peat moss because it will clog up your soil. Otherwise, akadama, lava, and fine pine bark should work well. The pine bark will add acidity to your soil without clogging it.

The best time to repot Japanese maples is the spring as they are just starting to come out of dormancy. You do NOT want to repot in Autumn as the trees are going INTO dormancy, since you don't want to mess with the roots or cause damage to the tree that it will not be able to recover from prior to winter dormancy. You want your deciduous trees to be at their strongest going into winter.

So with regards to my deshojo maple, if I repot now will that be a bad move . I'm just past spring. So plenty time for roots to form still . At the moment the soil it is in is well draining but looks tired and the plant is not really doing very much anyway at the minute like all my others which I will wait till next spring .

 

[leatherback]

The thing I don't really understand is how the UK zone9 climate is wildly different to a USA zone 9 but they're both zone 9

These zones are mostly defined by lowest temperatures reached in winter. Not the duration of those temperatures. So a spot with a -20C dip every 5 years vss a zone with -20 frost for weeks on end every year could be in the same climatic zone. Yet are experienced very differently.

Long term survival of maples is linked to drainage. Wet cold airless soil is host to growing out fungi that cause verticillium wilt (https://en.wikipedia.org/wiki/Verticillium_wilt). SO make sure you have a well draining substrate.

 

[Bonsainoob88]

I would skip the peat moss because it will clog up your soil. Otherwise, akadama, lava, and fine pine bark should work well. The pine bark will add acidity to your soil without clogging it.

The best time to repot Japanese maples is the spring as they are just starting to come out of dormancy. You do NOT want to repot in Autumn as the trees are going INTO dormancy, since you don't want to mess with the roots or cause damage to the tree that it will not be able to recover from prior to winter dormancy. You want your deciduous trees to be at their strongest going into winter.

At what ratio would you make that mix ?

 

[Bonsai Nut]

At what ratio would you make that mix ?

I would want equal parts pumice and lava, and then adjust the amount of fine bark based on the size of the bark. Perhaps 1/4 bark(?) You want the soil to be primarily grit with a minority of organic material.

 

[Bonsainoob88]

I would want equal parts pumice and lava, and then adjust the amount of fine bark based on the size of the bark. Perhaps 1/4 bark(?) You want the soil to be primarily grit with a minority of organic material.

Ok before you had a chance to answer I have repotted and root pruned a little bit . The tree as I suspected was root bound or getting close . So I have repotted using 50% akadama , 30% pumice , 20% pine bark.
I realised after saying I had lava rock that I actually had akadama and pumice, not lava rock !

I could of went on forever researching soils and different types and it just keeps getting more and more confusing the more I read . As I suppose things work differently for different people and I don't want to miss my opportunity to repot . So here we have it . My 1st repotted tree , let's see how this works out

 

[Bonsai Nut]

akadama and pumice, not lava rock !

The base for many mixes is 1/3 akadama, 1/3 pumice, 1/3 lava. In the case of acid-loving trees like azaleas, you would swap out kanuma for akadama.

However when I say "base" some people add other components, or change percentages. Additionally, piece size is really important. The larger the piece size, the better the drainage, but the faster it will dry out. Always screen your soil components to get rid of the dust and fines, and then screen it for piece size. I typically screen for two sizes and use the larger size for larger trees and smaller size for smaller trees.

 

[ConorDash]

I plan to use Akadama and Pumice for my new strategy next Spring, during repoting. I hear a lot about lava, but I wanted to start with a stable and reputable mix, 50/50 Akadama and Pumice. Medium size particle, both same same size.
The lava rock is the piece of the puzzle I am unsure about at the moment, but plenty of time to find out..

Root pruning and repoting a Maple in full growing mode, now? Interesting! Let us know how it responds in a month or 2. I'd like to know.

 

[Bonsainoob88]

I will do . Hopefully it wont die . But it wasn't doing anything much above the soil and was close to root bound in a tiny pot and it was drying out all the time . I think it would of eventually been dead anyway If I left it as I have a heavy schedule at work and cant water twice through the day .

 

[fredman]

I have repotted and root pruned a little bit

How much soil and roots did you remove exactly?

 

[Bonsainoob88]

How much soil and roots did you remove exactly?

Bare rooted, removed 100% soil . About 30% roots pruned

 

[fredman]

Interesting. I to will be very interested to know how it does. I bet on it pulling through, and be better off for it. Great soil you made there
Keep it moist, out the wind and sun and be sure to report back on it plz.

 

[Bonsainoob88]

Interesting. I to will be very interested to know how it does. I bet on it pulling through, and be better off for it. Great soil you made there
Keep it moist, out the wind and sun and be sure to report back on it plz.

I will do no problem, we will see

 

[Bonsainoob88]

Well , a good sign this morning, I checked the underside of my deshojo maple that I repotted and there are a few roots on site through the drainage holes which can only be a good thing . Hopefully it'll start pushing a bit new growth out before the fall then I know it is in good health . Also fitted a new water butt at weekend which filled in one night with a decent downpour. So soon It will be rainwater only for my maples